1. Field of the Invention
The present invention relates generally to pneumatic spray guns for spraying bulk material, and in particular to an improved bearing frame for a spray gun for spraying texturizing material from a hopper.
2. Description of the Related Art
Various types of finish and coating materials are commonly applied by spraying them onto surfaces which are to be finished or coated. Compressed air is often used for propelling paint and other finish materials. For example, paint is often applied in this manner using a compressor connected to a spray gun, which is also connected to a paint source.
Another example of a spray-applied finish is texturizing material of the type which is commonly applied to finished surfaces such as walls and ceilings in drywall construction and is generally liquidous, e.g., particles or granules mixed with water or relatively thin paint, the granules being variable in coarseness, texture, color, etc. Pneumatic spray guns can also be used for applying dry materials.
Pneumatic spray guns designed for such purposes often include air inlet openings for connection to compressors, material inlet openings for connection to material hoppers, and discharge orifices. Such spray guns typically include valve mechanisms for controlling their operation by selectively admitting air passage therethrough and opening the discharge orifices thereof.
The Masterson U.S. Pat. No. 4,863,104 discloses a fairly typical pneumatic spray gun apparatus of the type designed for applying texturizing material to walls, ceilings, etc. from a hopper. The Masterson spray gun apparatus includes an air valve operated by a trigger. When the air valve is open, a stream of air passes through the spray gun apparatus and receives material from a hopper supply. The air/material mixture exits the spray gun via a discharge orifice as a jet which can be directed onto the surface of a wall, ceiling, etc.
The present applicant also produced a spray gun of this general type, which included an air stem for continuously conveying an air stream through the spray gun and which slid within a pair of bearings. For proper operation, the bearings had to be aligned. Bearing misalignment could be caused by improper assembly, improper fit of the bearings within the body, and by external forces, such as the weight of the air hose tending to twist the rear/upstream bearing. Even a slight misalignment of the bearings in the applicant's prior art spray gun could cause the air stem to bind and drag, thus interfering with its effective operation and increasing wear on the bearings and the air stem, which slide relative to each other.
Moreover, the necessity of precisely aligning the bearings in applicant's previous spray guns required relatively tight tolerances in manufacturing and considerable care in assembly. With the bearing frame subassembly of the present invention, Applicant has found that greater precision can be achieved in aligning the bearings than with its previous design wherein the bearings were physically clamped in their operating positions by the assembled spray gun body.
The present invention relates to an improved bearing frame for such spray guns which tends to simplify their assembly, cleaning and maintenance and which tends to improve their operation.
Heretofore there has not been available a spray gun with an improved bearing frame with the advantages and features of the present invention.